I have been creating my own personalities for the Arri Sky Panel for the last couple of years.I am using Nic Morris's latest Sky Panel Personality as a reference for some of the features.I am basically making the personality more film and TV friendly, for example giving actual CCT values such as 5600K or 4300K as opposed to a value between 0 and 100.Not to dis Nic, whose work is amazing useful as you'll all agree.

However my question:

Can I tweek a created attribute and have that tweek reflected in the compiles modes, or do I have to re compile the mode to update the tweaks that I have made?

I'm not sure what you mean by recompile. Personality Builder generates xml (.d4) files for Titan or, essentially just text files (.R20) for Classic. You can edit the files directly in a text or xml editor but for .d4 I would just load the file into Personality Builder, add some fixed (text only) functions to the CCT control as required and then save. You could either do this via [Edit Personality] in Titan which will then provide an option to update in the current show when you save or load it separately and then use the [Update Personality] function to update in your show.

Note that if the scale is linear it is also possible to change the wheel display to a custom range. I suspect it isn't but you can do this by selecting the function in the attribute tree, then in the function properties expand the 'Display Type' section and change type to 'Custom Range'. According to the latest charts for the S60 the range is 0-255 = 2800 -> 10000K. So you would have DMX Start 0, End 255, Display Type 'Custom Range', Decimal Places 'One', Range Start 2800, Range End 10000, Diamond 4 Display Text %.1fK (the latter will result in displaying a value from the display range to a resolution of 1 decimal place immediately followed by a 'K'). Note that all of these can be set in the DMX Values grid except for Custom Range in Range Display.

Thanks fore this,I'm pretty much across custom values. I am showing HSI values as degrees 360 for example.In my custom CCT values, I am providing presets for 2700L 3200K 4000K 4300K 5600K etc. as well as an overriding 0-255 whole range slider. It is working very well.

My question (hopefully more clearly as an example):

In 'Fan Spd' created attribute - I remove one of the preset values ('Fan Off' for instance), This preset value has now been removed from the created attribute.Do I now need to rebuild all the mode lists that use this created attribute, or will it automatically update all the mode lists making use of this attribute?

It's automatic. The modes reference the attributes. When changing functions make sure that the locate values are still valid (particularly if a function has changed from variable to fixed or vice-versa), if it affects any macros, if it affects palettes and if it affects any conditions.